Turkish prosecutors have demanded two aggravated life sentences for a Greek airman who allegedly shot down a Turkish jet over the Aegean Sea in 1996. They also requested cooperation from Greece in launching legal action against the pilot.

Greek pilot Thanos Grivas was charged by Turkish prosecutors with “voluntary manslaughter,” “actions for weakening the independence of the state” and “vandalizing the jet,” the Hurriyet Daily reports, citing the indictment.

The charges were based on an incident that occurred in October 1996 and was referred to as a dogfight and aircraft accident in the legal documents. At that time, a Turkish F-16 fighter jet crashed to the south of the Greek island of Chios after an encounter with a Greek Mirage 2000 aircraft. The Turkish jet’s pilot, Captain Nail Erdogan, died in the incident while co-pilot Osman Cicekli was rescued.

The Turkish authorities now claim that Grivas deliberately shot down the F-16. Turkey opened a probe into the incident after the family and lawyer of the Turkish pilot who died in the crash addressed the Greek authorities, asking them to initiate legal proceedings against the Greek airman.

Ankara Public Prosecutor’s Office made an inquiry into the case by analyzing the radar data and conversation records from the two jets obtained from the Turkish General Staff. The Turkish jet’s co-pilot, Cicekli, also gave testimony and filed his own complaint against the Greek pilot.

“It was determined that the jet caught fire and crashed by burning when conversation records of the pilots and radar were examined. In the testimony, Lt. Col. Çiçekli said they were shot down by a missile fired from one of the jets without motive in international airspace,” Hurriyet reports, citing Turkish authorities.

Meanwhile, the lawyer for Erdogan family, Mehmet Emin Keles, said that the trial would be held in Turkey if Greece does not take action, citing a judicial assistance agreement between Greece and Turkey.

The Greek Council of Appeals Court rejected Turkey’s request concerning the pilot, Greece’s Kathimerini Daily reports. Athens also denies the downing of the jet, and says that Turkish pilot reported a control failure. It also claims that the jet violated Greece’s airspace because one of the Turkish pilots was rescued in the Greek flight information region, RIA Novosti reports.

Turkey initiated legal proceedings against the Greek pilot during a period of increasingly tense relations between the two countries, which follows a series of Greek airspace violations by Turkish fighter jets.

In April, Athens News Agency reported at least three incidents of Turkish jets entering Greek airspace without “submitting a flight plan.” Similar incidents were recorded in February with up to 14 Turkish fighter jets entering Greek airspace at once.

When a Turkish jet downed a Russian Su-24 bomber over the Syrian border on November 24, 2015, Turkey did not raise the question of the responsibility of its pilot for actions that led to the destruction of the Russian aircraft and the death of its pilot.

Turkey has repeatedly claimed that it has nothing to apologize for, and has tried to shift the blame for the incident onto Russia by claiming that the bomber violated Turkish airspace – although it has never able to prove these allegations.

Moscow denies any violation of Turkish airspace and has demanded that Ankara arrest Turkish ultranationalist Alparslan Celik, who bragged about killing the pilot of the Su-24 downed by the Turkish Air Force.

This demand was also ignored by Turkey while Celik continued to give interviews and travel freely in Turkey and across the border into Syria. He was eventually arrested by Turkish authorities on unrelated charges on March 31. However, on May 10, the charges against him were dropped due to insufficient evidence.

The incident with the downing of the Russian bomber soured relations between the two countries, with Russia subsequently imposing sanctions against Turkey and suspending the visa-free regime, as well as introducing an embargo on a number of Turkish goods.